Electric switches

ABSTRACT

A push-button switch comprises a springy wire which constitutes a switch contact and is so shaped and arranged that in response to the depression of the push-button which is spring-biased a cam deflects the switch contact whereby the contact makes momentary contact with another switch contact to provide contacts closure. Thereafter during the depression of the push-button the first mentioned switch contact disengages from the other wire contact and the cam is shaped so that as the push-button restores to its unoperated position under the action of its biasing spring the springy wire switch contact is deflected without the momentary switching action being repeated.

United States Patent [191 Field ELECTRIC SWITCHES [75] Inventor: JohnRosslyn Field, Fareham,

England [73] Assignee: Plessey Handel Und Investments A.G., Zug,Switzerland 22 Filed: Jan. 18, 1973 21 Appl. No.: 324,795

[30] Foreign Application Priority Data Jan. 19, 1972 Great Britain2684/72 [52] US. Cl 200/160, 200/153 LA [51] Int. Cl. H01h 13/52 [58]Field of Search 200/160, 159 A, 159 R,

[56] References Cited UNITED STATES PATENTS 3,153,130 10/1964 Nenninger200/160 FOREIGN PATENTS OR APPLICATIONS 546,001 3/1956 Belgium 200/16011] 3,835,276 1451 Sept. 10,1974

1,901,469 8/1970 Germany 200/159 A i w fiesriasr- B99925: h e

Assistant Examiner-William J .Snith Attorney, Agent, or Firm-ScrivenerParker Scrivener and Clarke [57] ABSTRACT A push-button switch comprisesa springy wire which constitutes a switch contact and is so shaped andarranged that in response to the depressionof the push- -button which isspring-biased a cam deflects the switch contact whereby the contactmakes momentary contact with another switch contact to provide contactsclosure. Thereafter during the depression of the push-button the firstmentioned switch contact disengages from the other wire contact and thecam is shapedso that as the push-button restores to its unoperatedposition under the action of its biasing spring the springy wire switchcontact is deflected without the momentary switching action beingrepeated.

1 Claim, 8 Drawing Figures ELECTRIC SWITCHES DISCLOSURE:

This invention relates to electric switches of the push-button type andrelates more specifically to such switches which provide a momentaryswitching action during the operation thereof and which may beadvantageously employed in electronic keyboards affording so-called keyrollover facilities.

The present invention provides a simple and relatively inexpensivepush-button switch comprising at least one springy wire whichconstitutes a switch contact and which is so shaped and arranged that inresponse to the depression of the push-button which is spring-biased acam deflects said switch contact whereby the latter makes momentarycontact with or disengages from another switch contact to effectcontacts closure or contacts opening and thereafter during thedepression of the push-button the first switch contact is allowed torestore to its former position thereby disengaging from or engaging withsaid another contact the cam being shaped so that as the pushbuttonrestores to its unoperated position under the action of its biasingspring the springy wire switch contact is deflected without themomentary switching action being repeated.

In carrying out the invention it is preferred to arrange that both ofthe switch contacts are of springy wire in which case the contacts canbe of identical size and shape.

To facilitate deflection of the spring (s) by the cam the spring may beprovided with a deformation which is engaged by the cam as thepush-button is depressed. The cam may be formed integrally with thepush-button.

The invention will be better understood from the accompanying schematicdrawing in which:

FIGS. la, to 1d show cross-sectional views of a pushbutton keyswitchaccording to the invention in the unactuated and actuated stages; and,

FIGS. 2a to 2d show cross-sectional views corresponding to those ofFIGS. la and 1d but taken along lines at right-angles thereto.

Referring to the drawing a push-button keyswitch according to thepresent invention comprises an insulated push-button, part of which isshown at 1, which is biased upwards by means of a coiled depressionspring 2. The push-button is shown in its normal unoperated position inFIGS. la and 2a.

The switch has two cantilever contacts which consist of springy wires 3and 4 conveniently sealed through a base member 5 of the switch andbiased to the right as viewed in FIG. 2a. As can be seen in FIGS. la to1d the wire contacts 3 and 4 are deformed-at 6 and 7 so that asthe-push-button is depressed against the action of spring 2 cam surfaces8 and 9 engage the deformities 6 and 7 and the wire contacts 3 and 4 aredefelcted into contact with each other to effect contacts closure asshown in FIG. lb. By referring to FIGS. 2a and 2d it will be seen thatthe top end parts of the respective wire contacts 3 and 4 are bent at anangle to the main parts of the appertaining contacts so that electricalcontact is made in the FIG. 2b switch condition at the point where thetwo end parts 10 and 11 cross one another. Upon further depression ofthe push-button to its fully depressed state as depicted in FIGS. 10 and2c the deformities6 and 7 pass upwards beyond the cam surfaces 8 and 9so that the wire contacts 3 and 4 can now spring apart to interruptelectrical contact as shown in FIG. 1c.

Thus it will be appreciated tha the switch provides a momentary makecontact action during the depression of the push-button. When howeverthe pushbutton is released it restores upwards under the action ofspring 2 as shown in FIG. 1d towards the position shown in FIG. la. Asthe push-button moves upwards the wire contacts are deflected as shownin FIG. 2d slide around the cam without the contacts closing duringreturn of the switch to the condition shown in FIG. la.

The embodiment of the switch described above with reference to thedrawing is particularly useful in electronic keyboard applications andit presents a simple and relatively cheap construction of the switch. Aswill be apparent from the foregoing, although the particular contactaction provided by the switch specifically described is a make action itwill be clear that a break switching action or a change-over switchingaction could be provided.

What we claim is:

l. A push-button electric switch comprising a pair of identical springywire co-operating switch contact members having deformed parts which inresponse to the depression of the push-button which is springbiased aredeflected simultaneously by cam means on said button for causingmomentary contact make or momentary contact break and for permitting thepushbutton to restore to its unoperated position under the action of itsbiasing spring without causing said momentary switching action to berepeated.

1. A push-button electric switch comprising a pair of identical springywire co-operating switch contact members having deformed parts which inresponse to the depression of the push-button which is spring-biased aredeflected simultaneously by cam means on said button for causingmomentary contact make or momentary contact break and for permitting thepush-button to restore to its unoperated position under the action ofits biasing spring without causing said momentary switching action to berepeated.